drivers/rtc/rtc-isl1208.c: add alarm support

Add alarm/wakeup support to rtc isl1208 driver

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>